Atherosclerosis and cancer are the two major causes of morbidity and mortality in western societies. While there has been significant advance in the treatment of atherosclerosis there is still a great need for more effective treatment interventions.
The main mechanism by which atherosclerosis leads to morbidity and mortality is by narrowing the lumen of arteries and reducing the blood supply to the heart, brain and other vital organs. The factors associated with atherosclerosis include: High levels of cholesterol, triglycerides, low density lipoproteins (LDL) and low levels of high density lipoproteins (HDL).
Other factors are heredity, cigarette smoking, obesity, high blood pressure, reduced physical activity, high fat diets, and a high oxidation activity associated with the production of free radicals, leading to the oxidation of LDL, which accelerates the development of atherosclerotic lesions. Thus, J. Regnstrom et al., Lancet, Vol. 339, No. 8803, May 16, 1992, pp. 1183-86, reported that the susceptibility of LDL to in vitro oxidation in the presence of copper, which acts as a catalyst in the oxidation process, was correlated with the severity of their coronary artery sclerosis. J. T. Salonen et al, Lancet, Vol. 339, No. 8798, Apr. 11, 1992, pp. 883-87, found that the level of autoantibodies to oxidized LDL predicted the progression of atherosclerosis of the carotid artery (the artery that supplies blood to the brain). One likely mechanism in development of atherosclerotic lesions via the oxidation of LDL is the induction of an autoimmune process leading to the production of antibodies specific to oxidized LDL and propagation of the atherosclerotic lesion by the autoantibody binding to oxidized LDL. J. Regnstrom et al., supra, and T. Kita et al., Proceedings of the National Academy of Sciences USA, Vol. 84, 1987, pp. 5928-31. J. T. Salonen et al., Circulation, Vol. 86(3), September 1992, pp. 803-11 reported an association between the risk of heart attack and the level of iron in the blood, with the risk being particularly high when plasma levels of both iron and LDL were elevated.
A significant reduction in blood levels of LDL and cholesterol by diet and lipid reducing drugs was found to result in regression of atherosclerosis. G. Brown et al., New England Journal of Medicine, Vol. 323(19), Nov. 8, 1990, pp. 1289-1298. Oral lipid lowering drugs, such as Lovastatin, MSD (Mevacor.RTM., Merck), are risky and may cause liver damage. Their efficacy is relatively limited, even when they are taken in association with a strict diet. Lowering of LDL by extracorporeal treatment of blood, M. Strahilevitz, U.S. Pat. Nos. 4,375,414 and 4,813,924, and M. Strahilevitz, Atherosclerosis, Vol. 26, 1977, pp. 373-77, is significantly more effective in reducing blood cholesterol and LDL levels. H. Borberg et al., Journal of Clinical Apheresis, Vol. 4, 1988, pp. 59-65; R. L. Wingard et al., American Journal of Kidney Diseases, Vol. 18(5), 1991, pp. 559-65; V. Hombach et al., Dtsch Med. Wschr, Vol. 111(45), 1986, pp. 1709-15. LDL and cholesterol can be removed by affinity adsorption, utilizing as the adsorbent antibodies to LDL or other specific chemical adsorbents, such as dextran sulphate (M. Odaka et al., International Journal of Artificial Organs, Vol. 9, 1986, pp. 343-48) or heparin (D. J. Lupien et al., Pediatric Res., Vol. 14, 1980, pp. 113-17). LDL removal can also be achieved by heparin precipitation (D. Seidel et al., Journal of Clinical Apheresis, Vol. 4, 1988, pp. 78-81), and by double filtration plasmapheresis (S. Yokoyama et al., Arteriosclerosis, Vol. 5, Nov./Dec. 1985, pp. 613-22) as well as by plasma exchange (G. R. Thompson, Lancet 1981 I, pp. 1246-48).
The oral administration of vitamin E is associated with lower risk of coronary heart disease in men (E. B. Rinim et al., New England Journal of Medicine, Vol. 328(20), May 20, 1993, pp. 1450-56) and in middle aged women (M. J. Stampfer et al., New England Journal of Medicine, Vol. 328(20), May 20, 1993, pp. 1487-89). The mechanism of this protective effect is based on the antioxidant property of vitamin E, which inhibits the oxidation of LDL, thus exerting a protective effect from the development of atherosclerosis. The oxidation of LDL is catalyzed by heavy metals such as iron and copper. The removal of the metals by intravenous administration of chelating agents was reported to be effective in atherosclerotic vascular disease. E. Olszewer and J. P. Carter, Medical Hypotheses, Vol. 27(1), September 1988, pp. 41-49, and E. Cranton, "Bypassing Bypass," Hampton Road Publishers, Norfolk, Va., 1992. Others did not confirm these reports. S. R. Wirebaugh and D. R. Gerates, DICP, Vol. 24(1), January 1990, pp. 22-24.
The apparent minimal effect, or lack of effect, of intravenous chelation in the treatment of atherosclerosis can be overcome by extracorporeal chelation which significantly increases chelation efficacy and reduces significantly its toxicity. M. Strahilevitz, Lancet, Vol. 340, Jul. 25, 1992, p. 235.
Extracorporeal chelation with desferoxamine was highly effective and safe in reducing blood iron in the treatment of hemochromatosis, a disease caused by the accumulation of excess iron in the blood and body stores. J. L. Held et al., Journal of American Academy of Dermatologists, Vol. 28, 1993, pp. 253-54. Ambrus and Horvath in U.S. Pat. No. 4,612,122 also describe a specific column configuration that can be used for extracorporeal chelation. In this column the chelating agent is physically immobilized in the spongy outer part of an anisotropic (asymmetrical) membrane.
Chelating agents can also be utilized with the extracorporeal affinity adsorption devices of Strahilevitz, U.S. Pat. No. 4,375,414.
Coronary bypass surgery is effective in reducing symptomatology, but its effect on mortality is limited. J. H. O'Keefe, Jr. and B. D. McCallister, Editorial, Mayo Clinic Proceedings, Vol. 67, 1992, pp. 389-91, R. D. Simari et al., Mayo Clinic Proceedings, Vol. 67, April 1992, pp. 317-22.
Bypass surgery has no curative effect on the atherosclerotic disease process. The problem of post surgery atherosclerosis progression and the development of coronary or graft restenosis are major problems associated with bypass surgery. The need for effective means for reducing progression and inducing regression of atherosclerosis in patients following bypass surgery is well recognized, as is the need to further develop effective nonsurgical treatments that would replace bypass surgery in a significant proportion of patients that are currently being treated with bypass surgery, because of the lack of alternative effective medical treatment.
This is particularly relevant for candidates for bypass coronary surgery with moderately severe coronary occlusion that may not exhibit significant fibrotic changes in the atherosclerotic coronary lesions. Similar limitations to those of bypass surgery apply to percutaneous transluminal coronary angioplasty. Simari et al., supra. In this procedure, an inflatable balloon is inserted into the coronary occlusion site. As with bypass surgery, this procedure also has no effect on the atherosclerotic disease process, thus restenosis is a significant problem. While the risks associated with angioplasty are lower than with bypass surgery, this is also an invasive procedure associated with morbidity and mortality risks.
While current medical treatments, particularly when combinations of conventional treatments are utilized, have significant effect in reducing progression and in inducing regression of the atherosclerotic process (Brown et al., supra), there is a need to have more effective treatment methods, particularly for those who can not be treated with oral lipid lowering drugs because of liver toxicity, who are unable to maintain a strict diet, or who fail to improve with conventional treatment, including oral lipid lowering drugs and diet.
The utilization of extracorporeal affinity adsorption of LDL (Strahilevitz, supra) can lead to marked reduction in LDL level, thus to significant regression of atherosclerotic coronary lesions. Hombach et al., supra. However, the effect of affinity adsorption of LDL and cholesterol, while aimed at a major factor in atherosclerosis, hyperlipidemia, is selectively targeted on this factor. Even when (as usually is the case) the affinity LDL adsorption is utilized with other measures (diet, exercise etc.) the quantitative impact of these conventional treatment methods may not be sufficient. The availability of non-surgical methods that will have a significantly larger quantitative effect on additional factors that are involved in the etiology and pathogenesis of atherosclerosis is of great importance, in order to optimize the non-surgical and post-surgical treatment of atherosclerosis.